That unit looks really good and seem to run well. That said, those amp draw numbers sound awfully low. Based on general experience are you sure they're not more like 20mA and 80mA instead of 2 and 8? The varying performance between forward and reverse may have to do with coupler height. When the coupler height relative to the axle C/L is higher it will tend to pull strongest when the power truck is closest to the coupled end and pulling away, less when the power truck is furthest away from the coupled end and pulling away. It effects the weight/ friction on the wheels due to the effect of the leverage caused by the coupler height. Helps one way, hurts the other way.